Average Weather in Chiang Rai Thailand

In Chiang Rai, the wet season is oppressive and overcast, the dry season is mostly clear, and it is hot year round. Over the course of the year, the temperature typically varies from 56°F to 94°F and is rarely below 50°F or above 100°F.

Based on the tourism score, the best time of year to visit Chiang Rai for warm-weather activities is from early November to mid March.

Temperature

The hot season lasts for 2.0 months, from March 11 to May 12, with an average daily high temperature above 91°F. The hottest day of the year is April 11, with an average high of 94°F and low of 70°F.

The cool season lasts for 2.0 months, from November 22 to January 22, with an average daily high temperature below 83°F. The coldest day of the year is January 4, with an average low of 56°F and high of 81°F.

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Clouds

In Chiang Rai, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.

The clearer part of the year in Chiang Rai begins around October 21 and lasts for 6.1 months, ending around April 25. On February 21, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy77% of the time, and overcast or mostly cloudy23% of the time.

The cloudier part of the year begins around April 25 and lasts for 5.9 months, ending around October 21. On July 19, the cloudiest day of the year, the sky is overcast or mostly cloudy93% of the time, and clear, mostly clear, or partly cloudy7% of the time.

The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Chiang Rai varies very significantly throughout the year.

The wetter season lasts 5.5 months, from April 27 to October 11, with a greater than 35% chance of a given day being a wet day. The chance of a wet day peaks at 68% on August 12.

The drier season lasts 6.5 months, from October 11 to April 27. The smallest chance of a wet day is 2% on February 1.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 68% on August 12.

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Chiang Rai experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.1 months, from March 5 to December 8, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around August 21, with an average total accumulation of 9.5 inches.

The rainless period of the year lasts for 2.9 months, from December 8 to March 5. The least rain falls around February 5, with an average total accumulation of 0.2 inches.

Average Monthly Rainfall

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Sun

The length of the day in Chiang Rai varies over the course of the year. In 2019, the shortest day is December 22, with 10 hours, 56 minutes of daylight; the longest day is June 21, with 13 hours, 20 minutes of daylight.

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 5:40 AM on June 7, and the latest sunrise is 1 hour, 18 minutes later at 6:58 AM on January 17. The earliest sunset is at 5:39 PM on November 26, and the latest sunset is 1 hour, 24 minutes later at 7:04 PM on July 6.

The solar day over the course of the year 2019. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

Humidity

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The muggier period of the year lasts for 8.5 months, from March 20 to December 4, during which time the comfort level is muggy, oppressive, or miserable at least 28% of the time. The muggiest day of the year is July 31, with muggy conditions 100% of the time.

The least muggy day of the year is January 24, with muggy conditions 3% of the time.

The percentage of time spent at various humidity comfort levels, categorized by dew point.

Wind

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Chiang Rai experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 5.7 months, from February 21 to August 12, with average wind speeds of more than 3.5 miles per hour. The windiest day of the year is June 21, with an average hourly wind speed of 4.1 miles per hour.

The calmer time of year lasts for 6.3 months, from August 12 to February 21. The calmest day of the year is December 26, with an average hourly wind speed of 2.9 miles per hour.

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Chiang Rai varies throughout the year.

The wind is most often from the east for 2.4 weeks, from October 16 to November 2, with a peak percentage of 35% on October 18. The wind is most often from the north for 1.9 months, from November 2 to December 30, with a peak percentage of 37% on December 12. The wind is most often from the south for 9.5 months, from December 30 to October 16, with a peak percentage of 33% on January 1.

Wind Direction

The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Best Time of Year to Visit

To characterize how pleasant the weather is in Chiang Rai throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Chiang Rai for general outdoor tourist activities is from early November to mid March, with a peak score in the second week of February.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Chiang Rai for hot-weather activities is from early March to late April, with a peak score in the last week of March.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Growing Season

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

Temperatures in Chiang Rai are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.

The brighter period of the year lasts for 2.1 months, from March 1 to May 5, with an average daily incident shortwave energy per square meter above 6.0 kWh. The brightest day of the year is March 31, with an average of 6.3 kWh.

The darker period of the year lasts for 2.2 months, from July 5 to September 12, with an average daily incident shortwave energy per square meter below 4.9 kWh. The darkest day of the year is August 4, with an average of 4.6 kWh.

The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Chiang Rai are 19.909 deg latitude, 99.832 deg longitude, and 1,299 ft elevation.

The topography within 2 miles of Chiang Rai contains only modest variations in elevation, with a maximum elevation change of 230 feet and an average elevation above sea level of 1,303 feet. Within 10 miles contains only modest variations in elevation (2,579 feet). Within 50 miles contains large variations in elevation (6,437 feet).

The area within 2 miles of Chiang Rai is covered by cropland (61%), artificial surfaces (26%), and shrubs (13%), within 10 miles by cropland (62%) and trees (29%), and within 50 miles by trees (56%) and cropland (37%).

Data Sources

This report illustrates the typical weather in Chiang Rai, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There is only a single weather station, Chiang Rai, in our network suitable to be used as a proxy for the historical temperature and dew point records of Chiang Rai.

At a distance of 3 kilometers from Chiang Rai, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.

Other Data

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.